Tests for rule name matching using patterns

Modify the disabled_rules_using_regex test to
disabled_rules_using_substring with an appropriate substring.

Also add a test where rule names have regex chars and allow rule names
to have regex chars when parsing falco's output in tests. These changes
are future-looking in case we want to add back support for rule
enabling/disabling using regexes.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

test/falco_test.py

@@ -269,7 +269,7 @@ class FalcoTest(Test):
         triggered_rules = match.group(1)
 
         for rule, count in self.detect_counts.iteritems():
-            expected = '\s{}: (\d+)'.format(rule)
+            expected = '\s{}: (\d+)'.format(re.sub(r'([$\.*+?()[\]{}|^])', r'\\\1', rule))
             match = re.search(expected, triggered_rules)
 
             if match is None: